-- Spontaneous emission rate for hydrogen state 2p psi(n,l,m) = R(n,l) Y(l,m) R(n,l) = 2 / n^2 * a0^(-3/2) * sqrt((n - l - 1)! / (n + l)!) * (2 r / (n a0))^l * L(2 r / (n a0), n - l - 1, 2 l + 1) * exp(-r / (n a0)) L(x,n,m,k) = (n + m)! sum(k,0,n, (-x)^k / ((n - k)! (m + k)! k!)) Y(l,m) = (-1)^m sqrt((2 l + 1) / (4 pi) (l - m)! / (l + m)!) * P(l,m) exp(i m phi) -- associated Legendre of cos theta (arxiv.org/abs/1805.12125) P(l,m,k) = test(m < 0, (-1)^m (l + m)! / (l - m)! P(l,-m), 2^(-m) sin(theta)^m sum(k,0,l - m, (-1)^k (l + m + k)! / (l - m - k)! / (m + k)! / k! * ((1 - cos(theta)) / 2)^k)) -- E(n) returns the nth energy eigenvalue E(n) = -e^2 / (8 pi epsilon0 a0 n^2) -- integrate f I(f) = do( f = f r^2 sin(theta), -- multiply by volume element f = circexp(f), -- convert to exponential form f = defint(f,theta,0,pi,phi,0,2pi), f = integral(f,r), 0 - eval(f,r,0) -- return value ) psi2 = psi(2,1,0) -- try psi(2,1,1) and psi(2,1,-1) also psi1 = psi(1,0,0) f21 = conj(psi1) psi2 f21 x21 = I(r sin(theta) cos(phi) f21) y21 = I(r sin(theta) sin(phi) f21) z21 = I(r cos(theta) f21) print(x21,y21,z21) r21sq = conj(x21) x21 + conj(y21) y21 + conj(z21) z21 r21sq -- physical constants (c, e, h, and k are exact values) c = 299792458.0 meter / second e = 1.602176634 10^(-19) coulomb epsilon0 = 8.8541878128 10^(-12) farad / meter h = 6.62607015 10^(-34) joule second hbar = h / float(2 pi) k = 1.380649 10^(-23) joule / kelvin me = 9.1093837015 10^(-31) kilogram mp = 1.67262192369 10^(-27) kilogram mu = me mp / (me + mp) -- derived units coulomb = ampere second farad = coulomb / volt joule = kilogram meter^2 / second^2 volt = joule / coulomb -- base units (for printing) ampere = "ampere" kelvin = "kelvin" kilogram = "kilogram" meter = "meter" second = "second" pi = float(pi) -- use numerical value of pi a0 = 4 pi epsilon0 hbar^2 / (e^2 mu) omega21 = (E(2) - E(1)) / hbar "Spontaneous emission rate" A21 = e^2 / (3 pi epsilon0 hbar c^3) omega21^3 r21sq A21 "Mean interval" 1 / A21 Run